Description General description 3,3′,5,5′-Tetramethylbenzidine is a peroxidase sensitive dye. It is a better alternative to syringaldazine for the determination of chlorine in water due to its product stability and no interference from calcium and magnesium ions. Packaging 1, 5, 25 g in glass bottle 100 mg in glass bottle Application 3,3′,5,5′-Tetramethylbenzidine (TMB) is a noncarcinogenic substitute (Ames test negative) for benzidine suitable as peroxidase substrate for use in ELISA procedures. The substrate produces a soluble end product that is pale blue in color and can be read spectrophotometrically at 370 or 620-650 nm. The TMB reaction may be stopped with 2 M H2SO4 (resulting in a yellow color), and read at 450 nm. A sensitive and specific reagent for the detection of blood, assay of hemoglobin, assay of peroxidases.